Electrochemical Kinetic Property Determination of MIECs by Comprehensive Multi-physical Coupling Model

Abstract

Abstract Surface exchange and bulk diffusion coefficients are important electrochemical kinetic properties of mixed ionic-electronic conductors (MIECs), which are usually obtained through electrical conductivity relaxation (ECR) experiments. However, the extensively employed method is built upon the ideal diffusion described by Fick’s second law with linear absorbing boundary, which is almost impossible to achieve in actual experiments. To simulate the actual experiment system and improve the estiamtion accuracy, a comprehensive mathematical model is established to describe the coupled multi-physical processes involved, such as convection-diffusion in the surrounding atmosphere, surface exchange, bulk diffusion of MIECs, and heat transfer. A comparison between different models is carried out, and the results show that the new model established is more accurate and compatible with more complex conductivity curves.